U.S. patent number 7,049,761 [Application Number 09/782,375] was granted by the patent office on 2006-05-23 for light tube and power supply circuit.
This patent grant is currently assigned to Altair Engineering, Inc.. Invention is credited to Jean C. Raymond, Jos Timmermans.
United States Patent |
7,049,761 |
Timmermans , et al. |
May 23, 2006 |
**Please see images for:
( Certificate of Correction ) ** |
Light tube and power supply circuit
Abstract
The present invention provides a light tube for illumination by
a power supply circuit including a bulb portion and a pair of end
caps disposed at opposite ends of the bulb portion. A plurality of
light emitting diodes are disposed inside the bulb portion and in
electrical communication with the pair of end caps for illuminating
in response to electrical current to be received from the power
supply circuit.
Inventors: |
Timmermans; Jos (Dearborn,
MI), Raymond; Jean C. (Montreal, CA) |
Assignee: |
Altair Engineering, Inc. (Troy,
MI)
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Family
ID: |
26877466 |
Appl.
No.: |
09/782,375 |
Filed: |
February 12, 2001 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20020060526 A1 |
May 23, 2002 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60181744 |
Feb 11, 2000 |
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Current U.S.
Class: |
315/246; 315/291;
315/185S; 257/E25.028 |
Current CPC
Class: |
B60Q
3/80 (20170201); H05B 45/3578 (20200101); F21K
9/66 (20160801); F21V 15/015 (20130101); F21V
23/02 (20130101); F21K 9/275 (20160801); F21V
3/02 (20130101); F21V 19/003 (20130101); F21V
23/023 (20130101); F21K 9/60 (20160801); F21V
23/00 (20130101); H05B 47/10 (20200101); F21K
9/278 (20160801); F21K 9/90 (20130101); F21V
23/06 (20130101); F21S 4/28 (20160101); H05B
45/14 (20200101); F21V 23/009 (20130101); H05B
45/3725 (20200101); F21K 9/272 (20160801); H05B
45/325 (20200101); H05B 45/10 (20200101); F21V
19/008 (20130101); F21Y 2103/10 (20160801); F21Y
2115/10 (20160801); Y02B 20/30 (20130101); H01L
2924/0002 (20130101); H01L 25/13 (20130101); H01L
2924/0002 (20130101); H01L 2924/00 (20130101) |
Current International
Class: |
H05B
37/02 (20060101) |
Field of
Search: |
;315/146,291,185S,312,324,192,185R,295,246,187,294,56,200A,61
;340/815.45 ;362/488,240,219,800,369,545,288,249 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Web page at http://trucklite.com/leds14.html printed on Jan. 13,
2000. cited by other .
Web page at http://trucklite.com/leds2.html printed on Jan. 13,
2000. cited by other .
Web page at http://trucklite.com/leds4.html printed on Jan. 13,
2000. cited by other .
Web page at http://www.telecite.com/en/products/options_en.htm
printed on Jan. 13, 2000. cited by other .
Web page at http://www.dialight.com/trans.htm printed on Jan. 13,
2000. cited by other .
Web page at http://www.ledlights.com/replac.htm printed on Jan. 13,
2000. cited by other .
Ledtronics, apparently 1996 Catalog, apparently cover page and p.
10. cited by other.
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Primary Examiner: Lee; Wilson
Assistant Examiner: Tran; Chuc
Attorney, Agent or Firm: Young & Basile, P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
Ser. No. 60/181,744 filed Feb. 11, 2000.
Claims
What is claimed is:
1. A light device for illumination by a power supply circuit
comprising: a bulb portion, a first end cap disposed at one end of
the bulb portion, a second end cap disposed at an end of bulb
portion opposite the first end cap, the first and second end caps
forming a pair of end caps on opposite ends of the bulb portion;
and wherein the bulb portion and the pair of end caps are
dimensioned to be mounted in a fluorescent light tube socket, and a
plurality of light emitting diodes disposed inside the bulb
portion, the light emitting diodes in electrical communication with
the end cap for illuminating in response to electrical current
received from the power supply circuit, and wherein the plurality
of light emitting diodes is mounted an at least one circuit board;
and wherein each of the plurality of light emitting diodes is
mounted at an angular off-set from the circuit board to establish a
predetermined radiation pattern of light.
2. A light tube for illumination by a power supply circuit
comprising: a bulb portion, a first of end caps disposed at
opposite ends of the bulb portion, wherein each of the pair of end
caps is shaped to be coupled with a fluorescent light tube socket,
and a plurality of closely-spaced light emitting diodes disposed
inside the bulb portion and extending between the opposite ends of
the bulb portion, the light emitting diodes in electrical
communication with the pair of end caps for illuminating in
response to electrical current received from the power supply
circuit; and wherein each of the pair of end caps is an electrical
bi-pin connector.
3. In a replacement light tube for a fluorescent light fixture
having a light tube socket and a power supply circuit, the
improvement comprising: a plurality of closely-spaced light
emitting diodes disposed inside a bulb portion of the light tube
and in electrical communication with a pair of end caps coupled to
opposed ends of the bulb portion and engageable with the light tube
socket, the plurality of light emitting diodes operable to
illuminate in response to electrical current delivered by the
fluorescent light; and wherein each of the pair of end caps is an
electrical bi-pin connector.
4. The improvement of claim 3, wherein the plurality of light
emitting diodes is mounted to a circuit board.
5. The improvement of claim 4, wherein each of the plurality of
light emitting diodes is mounted at an angular off-set from the
circuit board to establish a predetermined radiation pattern of
light.
6. The light device of claim 1 wherein the plurality of light
emitting diodes is mounted on only one side of the at least one
circuit board.
7. The light device of claim 6 wherein the radiation pattern of
light from each of the plurality of light emitting diodes is
centered at a 90.degree. angle relative to the at least one circuit
board.
8. The light device of claim 1 wherein each of the plurality of
light emitting diodes is a white LED.
9. The light device of claim 1, wherein the plurality of light
emitting diodes is displaced substantially continuously between the
opposite ends of the bulb portion.
10. A light device for illumination by a power supply circuit
comprising: a bulb portion, a first end cap disposed at one end of
the bulb portion, and a plurality of light emitting diodes disposed
inside the bulb portion, the light emitting diodes in electrical
communication with the end cap for illumination in response to
electrical current received from the power supply circuit; and
wherein the plurality of light emitting diodes is mounted on at
least one circuit board; and wherein each of the plurality of light
emitting diodes is mounted at an angular off-set from the circuit
board to establish a predetermined radiation pattern of light; and
wherein each of the plurality of light emitting diodes is arranged
into one of a plurality of equidistantly-spaced light emitting
diode banks, each of the plurality of light emitting diode banks
comprising at least two light emitting diodes.
11. The improvement of claim 3 wherein the bulb portion is
annular.
12. The improvement of claim 3 wherein the electric current is a
direct current signal, the improvement further comprising: a
rectifier for converting an alternating current signal from the
fluorescent light fixture to the direct current signal.
13. In a replacement light tube for a flourescent light fixture
having a light tube socket and a power supply circuit, the
improvement comprising: a plurality of closely-spaced light
emitting diodes disposed inside a bulb portion of the light tube
and in electrical communication with a pair of end caps coupled to
opposed ends of the bulb portion and engageable with the light tube
socket, the plurality of light emitting diodes operable to
illuminate in response to electrical current delivered by the
flourescent light fixture wherein the electric current is a direct
current signal; a rectifier for converting an alternating current
signal from the fluorescent light fixture to the direct current
signal; and a pulse-width modulating circuit for receiving the
direct current signal and supplying a resulting modulated signal to
the plurality of light emitting diodes.
14. The improvement of claim 3 wherein each of the plurality of
light emitting diodes is a white LED.
15. In a replacement light tube for a flourescent light fixture
having a light tube socket and a power supply circuit, the
improvement comprising: a plurality of closely-spaced light
emitting diodes disposed inside a bulb portion of the light tube
and in electrical communication with a pair of end caps coupled to
opposed ends of the bulb portion and engageable with the light tube
socket, the plurality of light emitting diodes operable to
illuminate in response to electrical current delivered by the
flourescent light fixture; and wherein each of the plurality of
light emitting diodes is arranged into one of a plurality of spaced
light emitting diode banks, each of the plurality of light emitting
diode banks comprising at least two light emitting diodes.
16. The improvement of claim 4 wherein the plurality of light
emitting diodes is mounted on only one side of the circuit board to
emit light toward only one side of the bulb portion.
17. The improvement of claim 16 wherein the radiation pattern of
light from each of the plurality of light emitting diodes is
centered at a 90.degree. angle relative to the circuit board.
18. The light device of claim 1 wherein the bulb portion comprises
one of clear glass and frosted glass.
19. A retrofit LED light tube for replacing a light tube in a
fixture, the retrofit LED light tube comprising: a elongated
cylindrical transparent envelope, a base cap at an end of the
envelope, wherein the base cap is an electrical bi-pin connector
comprising a first pin and a second pin extending perpendicularly
from a surface of the base cap, wherein the first and second pins
are adapted to electrically communicate with a fluorescent light
socket; and at least one LED device in electrical communication
with the base cap, wherein the at least one LED device is
electrically connected to a rectifier and the at least one LED
device is further electrically connected to a pulse-width
modulating circuit receiving a direct current signal from the
rectifier and supplying a modulated signal to the at least one LED
device.
20. The retrofit light tube of claim 19, wherein the LED device
comprises a circuit board and a plurality of LEDs serially
connected to the circuit board.
21. The retrofit light tube of claim 19, further comprising:
current-limiting means coupled to the at least one LED device.
22. The retrofit light tube of claim 19 wherein the base cap has
circuitry means for connection with an AC source.
23. The light device of claim 1 wherein each of the plurality of
light emitting diodes is arranged into one of a plurality of spaced
light emitting diode banks, each of the plurality of light emitting
diode banks comprising at least two light emitting diodes.
24. The improvement of claim 3 wherein each of the plurality of
light emitting diodes is arranged into one of a plurality of spaced
light emitting diode banks, each of the plurality of light emitting
diode banks comprising at least two light emitting diodes.
25. The improvement of claim 24 wherein each of the plurality of
spaced light emitting diode banks is spaced equidistant from
adjacent ones of the plurality of spaced light emitting diode
banks.
26. The improvement of claim 15 wherein each of the plurality of
spaced light emitting diode banks is spaced equidistant from
adjacent ones of the plurality of spaced light emitting diode
banks.
Description
FIELD OF THE INVENTION
The present invention relates to a light tube illuminated by LEDs
(light emitting diodes) which are packaged inside the light tube
and powered by a power supply circuit.
BACKGROUND OF THE INVENTION
Conventional fluorescent lighting systems include fluorescent light
tubes and ballasts. Such lighting systems are used in a variety of
locations, such as buildings and transit buses, for a variety of
lighting purposes, such as area lighting or backlighting. Although
conventional fluorescent lighting systems have some advantages over
known lighting options, such as incandescent lighting systems,
conventional fluorescent light tubes and ballasts have several
shortcomings. Conventional fluorescent light tubes have a short
life expectancy, are prone to fail when subjected to excessive
vibration, consume high amounts of power, require a high operating
voltage, and include several electrical connections which reduce
reliability. Conventional ballasts are highly prone to fail when
subjected to excessive vibration. Accordingly, there is a desire to
provide a light tube and power supply circuit which overcome the
shortcomings of conventional fluorescent lighting systems. That is,
there is a desire to provide a light tube and power supply circuit
which have a long life expectancy, are resistant to vibration
failure, consume low amounts of power, operate on a low voltage,
and are highly reliable. It would also be desirable for such a
light tube to mount within a conventional fluorescent light tube
socket.
SUMMARY OF THE INVENTION
A light tube for illumination by a power supply circuit includes a
bulb portion and a pair of end caps disposed at opposite ends of
the bulb portion. A plurality of light emitting diodes are disposed
inside the bulb portion and in electrical communication with the
pair of end caps, which diodes illuminate in response to electrical
current received from the power supply circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
The description herein makes reference to the accompanying drawings
wherein like reference numerals refer to like parts throughout the
several views, and wherein:
FIG. 1 is a line drawing showing a light tube, in perspective view,
which in accordance with the present invention is illuminated by
LEDs packaged inside the light tube;
FIG. 2 is a perspective view of the LEDs mounted on a circuit
board;
FIG. 3 is a cross-sectional view of FIG. 2 taken along lines
3--3;
FIG. 4 is a fragmentary, perspective view of one embodiment of the
present invention showing one end of the light tube disconnected
from one end of a light tube socket;
FIG. 5 is an electrical block diagram of a first power supply
circuit for supplying power to the light tube;
FIG. 6 is an electrical schematic of a switching power supply type
current limiter;
FIG. 7 is an electrical block diagram of a second power supply
circuit for supplying power to the light tube;
FIG. 8 is an electrical block diagram of a third power supply
circuit for supplying power to the light tube;
FIG. 9 is a fragmentary, perspective view of another embodiment of
the present invention showing one end of the light tube
disconnected from one end of the light tube socket; and
FIG. 10 is an electrical block diagram of a fourth power supply
circuit for supplying power to the light tube.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a line drawing showing a light tube 20 in perspective
view. In accordance with the present invention, the light tube 20
is illuminated by LEDs 22 packaged inside the light tube 20. The
light tube 20 includes a cylindrically shaped bulb portion 24
having a pair of end caps 26 and 28 disposed at opposite ends of
the bulb portion. Preferably, the bulb portion 24 is made from a
transparent or translucent material such as glass, plastic, or the
like. As such, the bulb material may be either clear or
frosted.
In a preferred embodiment of the present invention, the light tube
20 has the same dimensions and end caps 26 and 28 (e.g. electrical
male bi-pin connectors, type G13) as a conventional fluorescent
light tube. As such, the present invention can be mounted in a
conventional fluorescent light tube socket (not shown).
The line drawing of FIG. 1 also reveals the internal components of
the light tube 20. The light tube 20 further includes a circuit
board 30 with the LEDs 22 mounted thereon. The circuit board 30 and
LEDs 22 are enclosed inside the bulb portion 24 and the end caps 26
and 28.
FIG. 2 is a perspective view of the LEDs 22 mounted on the circuit
board 30. A group of LEDs 22, as shown in FIG. 2, is commonly
referred to as a bank or array of LEDs. Within the scope of the
present invention, the light tube 20 may include one or more banks
or arrays of LEDs 22 mounted on one or more circuit boards 30. In a
preferred embodiment of the present invention, the LEDs 22 emit
white light and, thus, are commonly referred to in the art as white
LEDs. In FIGS. 1 and 2, the LEDs 22 are mounted to one surface 32
of the circuit board 30. In a preferred embodiment of the present
invention, the LEDs 22 are arranged to emit or shine white light
through only one side of the bulb portion 24, thus directing the
white light to a predetermined point of use. This arrangement
reduces light losses due to imperfect reflection in a conventional
lighting fixture. In alternative embodiments of the present
invention, LEDs 22 may also be mounted, in any combination, to the
other surfaces 34, 36, and/or 38 of the circuit board 30.
FIG. 3 is a cross-sectional view of FIG. 2 taken along lines 3--3.
To provide structural strength along the length of the light tube
20, the circuit board 30 is designed with a H-shaped cross-section.
To produce a predetermined radiation pattern or dispersion of light
from the light tube 20, each LED 22 is mounted at an angle relative
to adjacent LEDs and/or the mounting surface 32. The total
radiation pattern of light from the light tube 20 is effected by
(1) the mounting angle of the LEDs 22 and (2) the radiation pattern
of light from each LED. Currently, white LEDs having a viewing
range between 6.degree. and 45.degree. are commercially
available.
FIG. 4 is a fragmentary, perspective view of one embodiment of the
present invention showing one end of the light tube 20 disconnected
from one end of a light tube socket 40. Similar to conventional
fluorescent lighting systems and in this embodiment of the present
invention, the light tube socket 40 includes a pair of electrical
female connectors 42 and the light tube 20 includes a pair of
mating electrical male connectors 44.
Within the scope of the present invention, the light tube 20 may be
powered by one of four power supply circuits 100, 200, 300, and
400. A first power supply circuit includes a power source and a
conventional fluorescent ballast. A second power supply circuit
includes a power source and a rectifier/filter circuit. A third
power supply circuit includes a DC power source and a PWM (Pulse
Width Modulation) circuit. A fourth power supply circuit powers the
light tube 20 inductively.
FIG. 5 is an electrical block diagram of a first power supply
circuit 100 for supplying power to the light tube 20. The first
power supply circuit 100 is particularly adapted to operate within
an existing, conventional fluorescent lighting system. As such, the
first power supply circuit 100 includes a conventional fluorescent
light tube socket 40 having two electrical female connectors 42
disposed at opposite ends of the socket. Accordingly, a light tube
20 particularly adapted for use with the first power supply circuit
100 includes two end caps 26 and 28, each end cap having the form
of an electrical male connector 44 which mates with a corresponding
electrical female connector 42 in the socket 40.
The first power supply circuit 100 also includes a power source 46
and a conventional magnetic or electronic fluorescent ballast 48.
The power source 46 supplies power to the conventional fluorescent
ballast 48.
The first power supply circuit 100 further includes a
rectifier/filter circuit 50, a PWM circuit 52, and one or more
current-limiting circuits 54. The rectifier/filter circuit 50, the
PWM circuit 52, and the one or more current-limiting circuits 54 of
the first power supply circuit 100 are packaged inside one of the
two end caps 26 or 28 of the light tube 20.
The rectifier/filter circuit 50 receives AC power from the ballast
48 and converts the AC power to DC power. The PWM circuit 52
receives the DC power from the rectifier/filter circuit 50 and
pulse-width modulates the DC power to the one or more
current-limiting circuits 54. In a preferred embodiment of the
present invention, the PWM circuit 52 receives the DC power from
the rectifier/filter circuit 50 and cyclically switches the DC
power on and off to the one or more current-limiting circuits 54.
The DC power is switched on and off by the PWM circuit 52 at a
frequency which causes the white light emitted from the LEDs 22 to
appear, when viewed with a "naked" human eye, to shine
continuously. The PWM duty cycle can be adjusted or varied by
control circuitry (not shown) to maintain the power consumption of
the LEDs 22 at safe levels.
The DC power is modulated for several reasons. First, the DC power
is modulated to adjust the brightness or intensity of the white
light emitted from the LEDs 22 and, in turn, adjust the brightness
or intensity of the white light emitted from the light tube 20.
Optionally, the brightness or intensity of the white light emitted
from the light tube 20 may be adjusted by a user. Second, the DC
power is modulated to improve the illumination efficiency of the
light tube 20 by capitalizing upon a phenomenon in which short
pulses of light at high brightness or intensity to appear brighter
than a continuous, lower brightness or intensity of light having
the same average power. Third, the DC power is modulated to
regulate the intensity of light emitted from the light tube 20 to
compensate for supply voltage fluctuations, ambient temperature
changes, and other such factors which effect the intensity of white
light emitted by the LEDs 22. Fourth, the DC power is modulated to
raise the variations of the frequency of light above the nominal
variation of 120 to 100 Hz thereby reducing illumination artifacts
caused by low frequency light variations, including interactions
with video screens. Fifth, the DC power may optionally be modulated
to provide an alarm function wherein light from the light tube 20
cyclically flashes on and off.
The one or more current-limiting circuits 54 receive the
pulse-width modulated or switched DC power from the PWM circuit 52
and transmit a regulated amount of power to one or more arrays of
LEDs 22. Each current-limiting circuit 54 powers a bank of one or
more white LEDs 22. If a bank of LEDs 22 consists of more than one
LED, the LEDs are electrically connected in series in an anode to
cathode arrangement. If brightness or intensity variation between
the LEDs 22 can be tolerated, the LEDs can be electrically
connected in parallel.
The one or more current-limiting circuits 54 may include (1) a
resistor, (2) a current-limiting semiconductor circuit, or (3) a
switching power supply type current limiter.
FIG. 6 is an electrical schematic of a switching power supply type
current limiter 56. The limiter 56 includes an inductor 58,
electrically connected in series between the PWM circuit 52 and the
array of LEDs 22, and a power diode 60, electrically connected
between ground 62 and a PWM circuit/inductor node 64. The diode 60
is designed to begin conduction after the PWM circuit 52 is
switched off. In this case, the value of the inductor 58 is
adjusted in conjunction with the PWM duty cycle to provide the
benefits described above. The switching power supply type current
limiter 56 provides higher power efficiency than the other types of
current-limiting circuits listed above.
FIG. 7 is an electrical block diagram of a second power supply
circuit 200 for supplying power to the light tube 20. Similar to
the first power supply circuit 100, the second power supply circuit
200 includes a conventional fluorescent light tube socket 40 having
two electrical female connectors 42 disposed at opposite ends of
the socket 40. Accordingly, a light tube 20 particularly adapted
for use with the second power supply circuit 200 includes two end
caps 26 and 28, each end cap having the form of an electrical male
connector 44 which mates with a corresponding electrical female
connector 42 in the socket 40.
In the second power supply circuit 200, the power source 46
supplies power directly to the rectifier/filter circuit 50. The
rectifier/filter circuit 50, the PWM circuit 52, and the one or
more current-limiting circuits 54 operate as described above to
power the one or more arrays of LEDs 22. The rectifier/filter
circuit 50, the PWM circuit 52, and the one or more
current-limiting circuits 54 of the second power supply circuit 200
are preferably packaged inside the end caps 26 and 28 or the bulb
portion 24 of the light tube 20 or inside the light tube socket
40.
FIG. 8 is an electrical block diagram of a third power supply
circuit 300 for supplying power to the light tube 20. Similar to
the first and second power supply circuits 100 and 200, the third
power supply circuit 300 includes a conventional fluorescent light
tube socket 40 having two electrical female connectors 42 disposed
at opposite ends of the socket 40. Accordingly, a light tube 20
particularly adapted for use with the third power supply circuit
300 includes two end caps 26 and 28, each end cap having the form
of an electrical male connector 44 which mates with a corresponding
electrical female connector 42 in the socket 40.
The third power supply circuit 300 includes a DC power source 66,
such as a vehicle battery. In the third power supply circuit 300,
the DC power source 66 supplies DC power directly to the PWM
circuit 52. The PWM circuit 52 and the one or more current-limiting
circuits 54 operate as described above to power the one or more
arrays of LEDs 22. In the third power supply circuit 300, the PWM
circuit 52 is preferably packaged in physical location typically
occupied by the ballast of a conventional fluorescent lighting
system while the one or more current-limiting circuits 54 and LEDs
22 are preferably packaged inside the light tube 20, in either one
of the two end caps 26 or 28 or the bulb portion 24.
FIG. 9 is a fragmentary, perspective view of another embodiment of
the present invention showing one end of the light tube 20
disconnected from one end of the light tube socket 40. In this
embodiment of the present invention, the light tube socket 40
includes a pair of brackets 68 and the light tube 20 includes a
pair of end caps 26 and 28 which mate with the brackets 68.
FIG. 10 is an electrical block diagram of a fourth power supply
circuit 400 for supplying power to the light tube 20. Unlike the
first, second, and third power supply circuits 100, 200, and 300
which are powered through direct electrical male and female
connectors 44 and 42, the fourth power supply circuit 400 is
powered inductively. As such, the fourth power supply circuit 400
includes a light tube socket 40 having two brackets 68 disposed at
opposite ends of the socket 40. At least one bracket 68 includes an
inductive transmitter 70. Accordingly, a light tube 20 particularly
adapted for use with the fourth power supply circuit 400 has two
end caps 26 and 28 with at least one end cap including an inductive
receiver or antenna 72. When the light tube 20 is mounted in the
light tube socket 40, the at least one inductive receiver 72 in the
light tube 20 is disposed adjacent to the at least one inductive
transmitter 70 in the light tube socket 40.
The fourth power supply circuit 400 includes the power source 46
which supplies power to the at least one inductive transmitter 70
in the light tube socket 40. The at least one transmitter 70
inductively supplies power to the at least one receiver 72 in one
of the end caps 26 and/or 28 of the light tube 20. The at least one
inductive receiver 72 supplies power to the rectifier/filter
circuit 50. The rectifier/filter circuit 50, PWM circuit 52, and
the one or more current-limiting circuits 54 operate as described
above to power the one or more arrays of LEDs 22. In this manner,
the light tube 20 is powered without a direct electrical
connection.
* * * * *
References